Currently, a computer is normally equipped with one display having a single-screen, but when a plurality of windows are required to be opened, they have to be switched on the display and are crowded, especially in a case in which analysis of graphs or a testing of programs is performed, the single-screen display is not suitable any more. Therefore a multi-screen (dual-screen or more than two screens) display appears. However, there are potential differences among the multi screens and pictures would render a mura phenomenon; Further, for the display with the multi screens sharing one power supply, it tends to occur mutual signal interferences among the multi screens.